1. Field of the Invention
The present invention relates generally to rear wheel suspension systems for vehicles and more particularly to an independent rear wheel suspension for vehicles.
2. Description of Relevant Art
In vehicles with some of the conventional independent rear wheel suspension systems of double Wishbone type there has been an unfavorable characteristic that the rear wheels tend to toe out when they bump and rebound. The present applicant has disclosed an independent rear wheel suspension which can eliminate such shortcoming, in UK Patent Application Publication No. GB A 2147553, published May 15, 1985. In this suspension, a knuckle which supports one of the rear wheels of a vehicle is pivotably attached in a vertically movable manner to a side of the vehicle body by using a trailing arm extending in the longitudinal direction of the vehicle, a long rear lower arm extending in the transverse direction of the vehicle, a short front lower arm arranged in front of the rear lower arm, substantially in parallel therewith, and an upper arm. The front lower arm functions as a compensation link. The trailing arm consists of a member, like a plate spring, this is at least partially sufficiently resilient in the transverse direction of the vehicle and highly rigid in the vertical direction thereof. By such suspension system, the rear wheels are adapted to toe in when they bump and rebound.
Moreover, in Japanese Patent Application Lay-Open Print No. 60-67205, laid open Apr. 17, 1985, the present applicant has proposed an independent rear wheel suspension which resembles the suspension of the above UK Publication and includes a front lower arm shorter than a rear lower arm. According to this Japanese Lay-Open Print, the short front lower arm permits a sufficient space to be secured for installation of a fuel tank in the rear part of a vehicle.
In the UK Publication above, when bumping and rebounding, the rear wheels tend to have their vibrations transmitted to a passenger accommodating space within the vehicle via the trailing and front and lower arms disposed near to the passenger space. The trailing arm and front lower arm as well as the upper arm and rear lower arm are, therefore, pivotably connected to the vehicle body side through elastic members, respectively.
The rear wheel toe angle characteristic depends on the rigidity of the trailing arm and the dimensions and installed positions of the lower arms. With respect to the toe angle characterisitc, there is a desideratum for increased freedom of design.
A further disadvantage of the suspension disclosed in the UK Publication above is the fact that the trailing arm is secured to the knuckle and hence, in the transverse direction of the vehicle in which it is resilient, its sympathetic vibration may sometimes be insufficiently controlled to maintain a comfortable ride. In this respect, there is a desideratum for effective control of such vibration of the trailing arm as well as for an enhanced riding comfort.
Similar disiderata are found also in the Japanese Lay-Open Print described.
The present invention has been achieved to provide an improved independent rear wheel suspension with respect to such desiderata in the UK Publication and Japanese Lay-Open Print as described.